Sulfur defect–engineered Bi2S3–x/In2S3–y mediated signal enhancement of photoelectrochemical sensor for lead ions detection

Lead ions (Pb2+) are heavy metal ion that are harmful to living organisms and ecosystems. It is important to realize sensitive detection of Pb2+ in the environment. In this study, a signal enhancement photoelectrochemical (PEC) sensor with high sensitivity was constructed for the detection of Pb2+. Firstly, to obtain excellent electron transfer performance, sulfur defect–engineered Bi2S3–x/In2S3–y mediated signal enhancement formed by Bi2S3 and In2S3 with well–matched structure in terms of energy level as the substrate materials. In this case, the introduction of sulfur vacancies further affects the electronic structure of the material, which significantly improves the electrical conductivity and effectively increases the electron transfer rate. In addition, the as–synthesized Cu@Cu2O nanosphere is chosen as the marker to accelerate the electron transfer through the surface plasmon resonance effect of Cu. The constructed sensor was able to detect Pb2+ in the range of 1 ng mL−1–100 μg mL−1 with a limit of detection of 19.2 pg mL−1. The sensor exhibits good reproducibility, specificity, and stability, indicating such PEC sensor can achieve the sensitive detection of Pb2+ in the environment. This work paves a new way for the construction of PEC sensors and the specific PEC detection of Pb2+ in environmental waters.